I've installed 4 smart radiator thermostats without any problem. I decided to install 4 more in my parent's house and they have this kind of "key":
Is it possible to install it here?
That looks like a manual valve for a “one pipe” system. You cannot fit a Tado to it and will have to replace the valve body with a thermostatic valve first. Not sure if it’s even possible to get a TRV for a one pipe system, but probably depends on your country.
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